OLED, as a new type of display technology, has unique advantages such as self-illumination, wide viewing angle, low power consumption, high efficiency, thin, rich colors, fast response, extensive application temperature, low drive voltage, used to make flexible, bendable and transparent display panel and environmental friendliness, etc. Therefore, OLED technology can be applied to flat panel displays and new generation of lighting, or can be used as backlight of LCD.
OLED is a device made through spin-coating or depositing a layer of organic material between two metal electrodes. A classic three-layer OLED comprises a hole transport layer, a light emitting layer and an electron transport layer. The holes generating from the anode through the hole transport layer and the electrons generating from the cathode through the electron transport layer combine to form excitons in the light emitting layer, emitting light. By changing the material of the light emitting layer, the OLED can emit red light, green light and blue light. Therefore, stable, efficient organic light-emitting materials with pure colors play an important role in the application and promotion of OLEDs. Meanwhile, it is also very urgent for the application and promotion of large area of panel display in OLEDs.
Among three primary colors (red, blue, green), the red and green light materials have made great development, which also meet the market demands of the panels. There are a series of commercially available materials for the blue light materials, and distyryl-biphenyl (DPVBi) compounds produced by Idemitsu are widely used in the early period. The devices made by this type of compound have high efficiency, but these materials often have poor stability, and even worse, this type of compound often emits sky blue light, and often y>0.15 of the CIE value. Therefore, its poor stability and impure color greatly restrict the application of this type of compounds in the full-color display devices. Another type of blue-light material is the Kodak ADN and tetra-butyl perylene, but their luminous efficiency is relatively poor, thus, it cannot be widely used.
